• 한국정보기술응용학회:학술대회논문집
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• 한국정보기술응용학회 2002년도 추계공동학술대회 정보환경 변화에 따른 신정보기술 패러다임
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• pp.461-467
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• 2002

뇌에서 얻은 시계열 신호들은 대부분 불규칙하고 복잡한 파형을 가지고 있으며, 1980년대 중반까지만 해도 이러한 신호들은 확률론 과정(stochastic process)으로 발생된 '소음'(noise)으로 여겨졌다. 하지만 최근 들어 뇌에 관한 연구가 활발히 진행되었고 EEG를 이용한 생체신호의 비선형분석에 관한 연구가 진행되면서 뇌에서 발생되는 신호는 의미 있는 신호로 분석되어지고 있다. 이에 비선형 분석방법인 상관차원을 이용하여 라벤더 향기 전과 향기 후의 뇌파의 변화를 분석하고, 주파수 대역별로 delta파, theta파, alpha파, beta파로 나누어서 라벤더 향이 뇌에 미치는 영향을 분석한다. 즉, 뇌에서 발생되는 신호의 특징을 찾기 위해 다른 향보다 강하게 반응하는 라벤더 향을 후각자극으로 제시하여 EEG를 측정한 후, 16채널에 대한 상관차원을 구하고 라벤더 향이 뇌에 미치는 영향을 분석한다.

• 한국산업정보학회:학술대회논문집
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• 한국산업정보학회 2002년도 추계공동학술대회
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• pp.461-467
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• 2002

뇌에서 얻은 시계열 신호들은 대부분 불규칙하고 복잡한 파형을 가지고 있으며, 1980년대 중반까지만 해도 이러한 신호들은 확률론 과정(stochastic process)으로 발생된 '소음'(noise)으로 여겨졌다. 하지만 최근 들어 뇌에 관한 연구가 활발히 진행되었고 EEG를 이용한 생체신호의 비선형 분석에 관한 연구가 진행되면서 뇌에서 발생되는 신호는 의미 있는 신호로 분석되어지고 있다. 이에 비선형 분석방법인 상관차원을 이용하여 라벤더 향기 전과 향기 후의 뇌파의 변화를 분석하고, 주파수 대역별로 delta파, theta파, alpha파, beta파로 나누어서 라벤더 향이 뇌에 미치는 영향을 분석한다. 즉, 뇌에서 발생되는 신호의 특징을 찾기 위해 다른 향보다 강하게 반응하는 라벤더 향을 후각 자극으로 제시하여 EEG를 측정한 후, 16채널에 대한 상관차원을 구하고 라벤더 향이 뇌에 미치는 영향을 분석한다.

• 한국전자파학회논문지
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• 제24권1호
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• pp.36-46
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• 2013

본 논문은 휴대형 비선형 소자 탐지기용 광대역 스파이럴 안테나의 설계를 제안한 것이다. 광대역 안테나의 설계를 위해 방사면 위의 스파이럴 턴 수를 최적화하는 반복 계산이 고려되었다. 원형 편파 설계를 위해 접지면과 방사면 사이의 동일 전류 분포를 유지하기 위해 Archimedean 스파이럴 슬릿을 가진 접지면이 고려되었다. 또한, 고 이득과 고 지향성을 실현하기 위해 캐비티 벽과 금속 캡을 접지면 뒤에 고려하였다. 반사 손실의 측정결과는 관심 대역인 2.4~2.44 GHz, 4.84~4.92 GHz, 7.28~7.36 GHz에서 VSWR 2:1과 잘 일치하였다. 측정된 축비 값은 3 dB 이하로 관측되었고, 모의 실험 결과와도 잘 일치하였다. 관심 대역에서 6.8 dBi 이상의 측정된 이득을 가지는 우수 원형 편파 특성이 관측되었다.

• 치과방사선
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• 제24권2호
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• pp.337-345
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• 1994

Arthrography of the temporomandibular joint is a useful method of demonstrating the soft tissue abnormalities related to disc dysfunction. In this study, 19 asymptomatic joints, 31 joints with anterior disc displacement with reduction, 31 joints with anterior disc displacement without reduction which were classified by arthrotomography under fluoroscopy were evaluated to determine the linear measurement of anterior recess of inferior joint space and the relationship between the condylar anterior translation and the severity of the internal derangements. Their fluoroscopic images were also evaluated to describe the characteristics of condylar paths in internal derangements of the temporomandibular joints. The results were as follows; 1. The mean lengths of the anterior recess in asymptomaic group. reduction group. and non-reduction group were 8.7±1.6㎜. 11.2±1.7㎜, 12.8±1.7㎜ respectively. The length of the anterior recess was increased according to the severity of the internal derangements(P<0.05). 2. Linear measurements of anterior movement of condyle on maximum mouth opening were 13.1 ±4.2㎜, 15.9±4.1㎜, 5.0±3.7㎜ in asymptomatic group. reduction group, and non-reduction group respectively. Compared with asymptomatic group, reduction group showed hypermobolity of the condyle and non-reduction group showed hypomobility. 3. Condyles moved beyond the crest of articular eminence in 80% of reduction group and did not reach it in 70% of non-reduction group. 4. The condyle moved mainly superiorly in reduction group(66%) and horizontally in asymptomatic group(47%). There were no cases to move superiorly in non-reduction group.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.955-958
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• 2001

The structure characteristics of varistor of Zn oxide to depend on the breakdown voltage has been investigated to annealing condition by additive material of Sb$_2$O$_3$ system. The breakdown voltage that has not doping Sb$_2$O$_3$ was 235[V]. ZnO varistors was shown ohmic properties when it's applied voltage was below critical voltage. It was shown non-ohmic properties over critical voltage, because current was increased with decreasing resistance. High voltage ZnO varistors had high breakdown voltage, but it had bad electrical stability with various surge. Sb$_2$O$_3$was increased non-linear coefficient in ZnO varistors grain boundary.

• Computers and Concrete
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• 제17권1호
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• pp.107-127
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• 2016

Concrete is a heterogeneous material containing many weaknesses such as micro-cracks, pores and grain boundaries. The crack growth mechanism and failure behavior of concrete structures depend on the plastic deformation created by these weaknesses. In this article the non-linear finite element method is used to analyze the effect of presence of micro pore near a crack tip on both of the characteristics of crack tip plastic zone (its shape and size) and crack growth properties (such as crack growth length and crack initiation angle) under pure shear loading. The FE Code Franc2D/L is used to carry out these objectives. The effects of the crack-pore configurations and the spacing between micro pore and pre-excising crack tip on the characteristics of crack tip plastic zone and crack growth properties is highlighted. Based on the obtained results, the relative distance between the crack tip and the micro pore affects in very significant way the shape and the size of the crack tip plastic zone. Furthermore, crack growth length and crack initiation angle are mostly influenced by size and shape of plastic zone ahead of crack tip. Also the effects of pore decrease on the crack tip by variation of pore situation from linear to perpendicular configuration. The critical position for a micro pore is in front of the crack tip.

• 한국해양공학회지
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• 제12권3호통권29호
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• pp.19-30
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• 1998

In this paper, the dynamic analysis of a dolphin system for mooring a floating structure such as barge mounted plant is studied. The characteristics of the soil-pile system are simplified by a set of equivalent spring elements at the mudline. To evaluate the equivalent spring constants, the finite difference method is used. Since the characteristics of the soil-pile system are nonlinear in case of soft foundation, the nonlinear dynamic analysis technique is needed. The Newmark $beta$ method incorporating the modified Newton-Raphson method(initial stiffness method) is used. A numerical analysis is performed on two mooring dolphin systems on soft foundation and rock foundation. In case of the rock foundation, the characteristics are found to be nearly linear, so the linear dynamic analysis may be sufficient to consider the foundation effect. But in case of soft foundation, the non-linearity of the foundation appears to be very signigicant, so the nonlinear dynamic analysis si needed.

• 대한전기학회논문지:시스템및제어부문D
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• 제49권8호
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• pp.432-441
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• 2000

It is difficult to analyze the charging characteristics of the lead-acid battery, because of the influences by various non-linear and time-variant parameters. In this study, the charging characteristics of high capacity industrial lead-acid battery 630 Ah was investigated through experiments with respect to the variations of temperature and the aged state of battery during the charging process. The database of those characteristics is established from the results of experiments, and the fuzzy logic charging algorithm is suggested using them. The results of experiment shows that the industrial lead-acid batteries can be always fully charged within the saved charging time by the proposed charging control algorithm adapting to the variations of charging condition. This new charging concept will be useful for developing the advanced battery charger improving the efficiency of storing electricity.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 D
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• pp.2633-2635
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• 2003

In this study, we propose a fuzzy polynomial neural networks (FPNN) and a genetically optimized fuzzy polynomial neural networks(GoFPNN) for identification of non-linear system. GoFPNN architecture is designed by a FPNN based on fuzzy set and its structure and parameters are optimized by genetic algorithms. A fuzzy neural networks(FNN) based on fuzzy set divide into two structures that is simplified inference structure and linear inference structure. The proposed FPNN is resulted from integration and extension of simplified and linear inference structure of FNN. The consequence structure of the FPNN consist of polynomials represented by networks using connection weights for rules. The networks comprehend simplified(Type 0), linear (Type 1), and quadratic(Type 3) inferences. The proposed FPNN can select polynomial type of consequence part for each rule. Therefore, proposed scheme can offer flexible structure design capability for a system characteristics. Moreover, GAs is applied to networks structure and parameters tuning of proposed FPNN, and its efficient application method is discussed, these subjects are result in GoFPNN that is optimal FPNN. To evaluate proposed model performance, a numerical experiment is carried out.

• Earthquakes and Structures
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• 제24권6호
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• pp.455-475
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• 2023

The present study investigates the non-linear soil-pile interaction using three-dimensional (3D) non-linear finite element models. The numerical models were validated by using the results of extensive pile load and shaking table tests. The pile performance in liquefiable and non-liquefiable soil has been studied by analyzing the liquefaction ratio, pile lateral displacement (LD), pile bending moment (BM), and frictional resistance (FR) results. The pile models have been developed for the different ground conditions. The study reveals that the results obtained during the pile load test and shaking cycles have good agreement with the predicted pile and soil response. The soil density, peak ground acceleration (PGA), slenderness ratio (L/D), and soil condition (i.e., dry and saturated) are considered during modeling. Four ground motions are used for the non-linear time history analyses. Consequently, design charts are proposed depended on the analysis results to be used for design practice. Eleven models have been used to validate the capability of these charts to capture the soil-pile response under different seismic intensities. The results of the present study demonstrate that L/D ratio slightly affects the lateral displacement when compared with other parameters. Also, it has been observed that the increasing in PGA and decreasing L/D decreases the excess pore water pressure ratio; i.e., increasing PGA from 0.1 g to 0.82 g of loose sand model, decrease the liquefaction ratio by about 50%, and increasing L/D from 15 to 75 of the similar models (under Kobe earthquake), increase this ratio by about 30%. This study reveals that the lateral displacement increases nonlinearly under both dry and saturated conditions as the PGA increases. Similarly, it is observed that the BM increases under both dry and saturated states as the L/D ratio increases. Regarding the acceleration histories, the pile BM was reduced by reducing the acceleration intensity. Hence, the pile BM decreased to about 31% when the applied ground motion switched from Kobe (PGA=0.82 g) to Ali Algharbi (PGA=0.10 g). This study reveals that the soil conditions affect the relationship pattern between the FR and the PGA. Also, this research could be helpful in understanding the threat of earthquakes in different ground characteristics.